Total bridges
55
Public highway bridges in Winnebago County
County profile · official public datasets
Winnebago County, IA
55 public highway bridges tracked in the FHWA National Bridge Inventory: 30.9% rated Good, 36.4% Fair, 32.7% Poor.
- 55
- Public bridges
- 30.9%
- Good condition
- 32.7%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Winnebago County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.
- 87th
- of 99 on Poor share
- 32.7%
- Poor-condition share
- 55
- public highway bridges
- 1984
- avg year built
Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.
Winnebago County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Winnebago County ranks #87 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 32.7%). Winnebago County, Iowa contains 55 public highway bridges. Roughly 30.9% are rated “Good,” 36.4% “Fair,” and 32.7% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.
Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.
Source: FHWA National Bridge Inventory. See methodology for full definitions.
Good condition
30.9%
17 of 55 rated 7-9
Fair condition
36.4%
20 of 55 rated 5-6
Poor condition
32.7%
18 of 55 rated 4 or below
In-state Poor-share rank
#87 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 55 NBI-tracked bridges by lowest applicable component rating.
Good 30.9% (17)
Fair 36.4% (20)
Poor 32.7% (18)
Winnebago County's Poor-condition bridges carry 1,643 vehicle crossings a day
That is 6.1% of the county's reported daily bridge traffic on 32.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 91 crossings a day against 71 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.
Computed over the 55 of 55 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
29.1% of Winnebago County's bridges have passed the 50-year mark
16 of the 55 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 30.9% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.
Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.
One structure carries 57.1% of the county's Poor-condition bridge traffic
FM over BLUE EARTH RIVER, built 1924, carries 938 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 18-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 1,643 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Winnebago County's bridges were built
55 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s 1
1930–1939
1 bridges
- 1940s 2
1940–1949
2 bridges
- 1950s 3
1950–1959
3 bridges
- 1960s
1960–1969
5 bridges
- 1970s
1970–1979
10 bridges
- 1980s
1980–1989
7 bridges
- 1990s 4
1990–1999
4 bridges
- 2000s
2000–2009
7 bridges
- 2010s
2010–2019
11 bridges
- 2020s 2
2020–2029
2 bridges
What this shows Construction peaked in the 2010s, when 11 of the county's bridges still in the inventory were built, which is 20% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year is 1984, 5 years newer than the Iowa average of 1979.
How Winnebago County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Winnebago County in number of bridges, with their condition splits. Its 32.7% Poor share is the 6th-lowest of these 6. Its average build year of 1984 against a peer-group mean of 1973 is 11 years newer.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Monroe County | 130 | 26.2% | 49.2% | 24.6% | 1977 |
| Worth County | 116 | 35.3% | 48.3% | 16.4% | 1970 |
| Humboldt County | 87 | 36.8% | 52.9% | 10.3% | 1965 |
| Dickinson County | 84 | 40.5% | 41.7% | 17.9% | 1981 |
| Emmet County | 78 | 23.1% | 60.3% | 16.7% | 1973 |
| Winnebago County (this page) | 55 | 30.9% | 36.4% | 32.7% | 1984 |
Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Winnebago County's. Source: FHWA National Bridge Inventory, 2024 release.
Nationwide counties with similar inventory size or average build year
Two NBI-derived peer sets for Winnebago County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (55 bridges here).
- Park County, CO · 55 bridges
- Dixie County, FL · 55 bridges
- Logan County, KS · 55 bridges
- Gallatin County, KY · 55 bridges
Similar average build year
Nearest mean year-built outside IA (1984 here).
- Hennepin County, MN · avg 1984 · 936 bridges
- Duval County, FL · avg 1984 · 831 bridges
- El Paso County, CO · avg 1984 · 686 bridges
- Bell County, TX · avg 1984 · 660 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (55)
LOCAL
PoorOver: N BUFFALO CREEK
100253602, Winnebago, IA
Built 1949 Load: 24.1 t ADT: 11
FM
PoorOver: BLUE EARTH RIVER
099260902, Winnebago, IA
Built 1924 Load: 24.5 t ADT: 938
LOCAL
PoorOver: BEAVER CREEK
099233501, Winnebago, IA
Built 1976 Load: 24.7 t ADT: 41
LOCAL
PoorOver: DRAINAGE DITCH
098250601, Winnebago, IA
Built 1950 Load: 25.8 t ADT: 35
LOCAL
PoorOver: DRAINAGE DITCH
098260401, Winnebago, IA
Built 1985 Load: 29.3 t ADT: 26
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.